Attitudes toward homosexuals: An alternative darwinian view

Gallup (1995) argued that there has been selection for parents to counter any social process that would increase the likelihood of one of their children becoming homosexual, and he indicated that contact between adult homosexuals and children was such a process. He therefore predicted (and found) that homophobia would be exaggerated where there was perceived contact with children. In this commentary, I argue that this hypothesis is based on supposing that sexual orientation occurs through a modeling process, when in fact it operates via an imprinting-like process. The specific findings regarding negative attitudes to homosexuals can be explained in terms of a more general evolved response, xenophobia. I argue that Gallup's hypothesis comes from a general willingness to view specific aspects of contemporary human behavior as adaptive when there are a number of reasons—all consistent with modern Darwinian thinking—why many of these are not themselves adaptive.     

Testing Miller's theory of alleles preventing androgenization as an evolutionary explanation for the genetic predisposition for male homosexuality

The genetic background of male homosexuality presents an evolutionary paradox, since homosexuality could be considered a reproductive disadvantage. We tested E.M. Miller's (2000) balanced polymorphism explanation, which states that alleles partially preventing androgenization in male fetuses during pregnancy would be associated with a homosexual orientation. Having all the alleles produces homosexuality, while heterosexual carriers with only a few of these alleles instead have a reproductive advantage; that is, they have more traits, which, by controlling for excessive aggressiveness and psychopathy, make them more attractive mates. Pairs of brothers were used to test these assumptions. If homosexuality is due to having all the androgenization-preventing alleles, then heterosexual men with homosexual brothers are more likely to also have some of the these alleles compared to heterosexual men with heterosexual brothers. These two categories were compared on variables related both directly and indirectly to reproductive success, with heterosexual men with a homosexual brother hypothesized to have an advantage on the variables. However, no statistically significant findings in support of the theory were detected. The results were discussed together with alternative explanations.     

Attitudes toward homosexuals and evolutionary theory: The role of evidence

Archer (this issue) contends that seduction by homosexual pedophiles is largely a result of media exaggeration and that xenophobia explains the data I reported on attitudes toward homosexuals (Gallup 1995). However, a cursory review of the evidence shows that the incidence of child molestation by homosexual males is much higher than Archer implies, and when the specific findings on attitudes are considered, xenophobia fails to provide an adequate account of the way people react to homosexuals.     

Perceived Sexual Orientation Based on Vocal and Facial Stimuli Is Linked to Self-Rated Sexual Orientation in Czech Men

Previous research has shown that lay people can accurately assess male sexual orientation based on limited information, such as face, voice, or behavioral display. Gender-atypical traits are thought to serve as cues to sexual orientation. We investigated the presumed mechanisms of sexual orientation attribution using a standardized set of facial and vocal stimuli of Czech men. Both types of stimuli were rated for sexual orientation and masculinity-femininity by non-student heterosexual women and homosexual men. Our data showed that by evaluating vocal stimuli both women and homosexual men can judge sexual orientation of the target men in agreement with their self-reported sexual orientation. Nevertheless, only homosexual men accurately attributed sexual orientation of the two groups from facial images. Interestingly, facial images of homosexual targets were rated as more masculine than heterosexual targets. This indicates that attributions of sexual orientation are affected by stereotyped association between femininity and male homosexuality; however, reliance on such cues can lead to frequent misjudgments as was the case with the female raters. Although our study is based on a community sample recruited in a non-English speaking country, the results are generally consistent with the previous research and thus corroborate the validity of sexual orientation attributions.     

Is risk of Kaposi's sarcoma in AIDS patients in Britain increased if sexual partners came from United States or Africa?

OBJECTIVE--To determine whether the risk of Kaposi''s sarcoma in patients with AIDS is increased by sexual contact with groups from abroad with a high incidence of Kaposi''s sarcoma. DESIGN--Analysis of risk of Kaposi''s sarcoma in patients with AIDS, according to country of origin of their sexual partners. SETTING--United Kingdom. PATIENTS--2830 patients with AIDS reported to the Communicable Disease Surveillance Centre and the Communicable Disease (Scotland) Unit up to March 1990, of whom 566 had Kaposi''s sarcoma. MAIN OUTCOME MEASURES--Percentage of patients with AIDS who had Kaposi''s sarcoma. RESULTS--537 of 2291 homosexual or bisexual men (23%) with AIDS had Kaposi''s sarcoma; 10% (14/135) of the men and women who acquired HIV by heterosexual contact had Kaposi''s sarcoma. None of the 316 subjects who acquired HIV through non-sexual routes had Kaposi''s sarcoma. Kaposi''s sarcoma was more common among homosexual men whose likely source of infection included the United States (171/551, 31%) or Africa (9/34, 26%) than among those infected in the United Kingdom (119/625, 19%) (p less than 0.05). CONCLUSION--The data suggest that Kaposi''s sarcoma is caused by a sexually transmissible agent which was introduced into the British homosexual population mainly from the United States [corrected].     

Inter-Mount Social Interactions During Heterosexual and Homosexual Consortships in Japanese Macaques

In this study, we examined whether female Japanese macaques ( Macaca fuscata ) exhibited male-typical patterns of inter-mount social behaviour during homosexual consortships. Data were collected on heterosexual and homosexual consortships from a population of free-ranging Japanese macaques in Arashiyama, Japan. Inter-mount intervals were defined as the period between two consecutive mounts. A total of 3374 heterosexual inter-mount intervals and 1412 homosexual inter-mount intervals were analysed. We examined nine different categories of inter-mount behaviour. Sex differences between heterosexually consorting males and females existed for three of the inter-mount behaviours we examined (i.e. ventral-to-dorsal orientation, aggression directed toward third party individuals, tree-shaking displays). The subordinate female partners in homosexually consorting pairs exhibited some sex-atypical inter-mount behaviours. This sex-atypicality did not appear to reflect generalized developmental canalization in the direction of a male-typical suite of behaviours. Rather, the observed behavioural sex-atypicality could be best explained in terms of the unique alliance-related dynamics that characterized homosexual consortships in Japanese macaques.     

A comparison of heterosexual and homosexual mating preferences in personal advertisements

Human heterosexual mating preferences have been shown to conform to predictions drawn from evolutionary theory, with men and women adopting broadly distinct strategies. Attempts to reconcile sexual selection theory with homosexual behavior have been less consistent, however, and have largely focussed on addressing two alternative perspectives: (i) that gay men and lesbians display phenotypic traits in common with opposite sex heterosexual individuals or (ii) that homosexual individuals display sex-typical, or exaggerated sex-typical phenotypes. Testing these hypotheses is complicated by sampling issues involved in the study of human sexual orientation, since obtaining standardized and comparable samples of heterosexual and non-heterosexual mating preferences is a prerequisite to analysis. Here we present a comparison of homosexual and heterosexual mating strategies in men and women using a sample of 1733 personal (‘lonely hearts’) adverts gathered from a single source. We used principal components analysis in order to expose underlying structure of the advertisements, and identify three components involving relative emphasis placed on resources, physical attractiveness and personality when offering or seeking mate characteristics. While homosexual individuals are shown to resemble their own-sex heterosexual counterparts in terms of emphasis placed on partner physical attractiveness relative to partner personality, no clear pattern emerges in other aspects of advertisement strategy. Nevertheless, there we find no evidence in support of the hypothesis that homosexual men and women are intrinsically opposite-sex typical in terms of mate preferences.     

Disclosure of sexual preference to physicians by black lesbian and bisexual women.

Physicians'' ability to diagnose and treat health care problems, particularly those with a psychosocial component, is facilitated by accurate information concerning the life-styles of their patients. White lesbians have been shown to be generally reluctant to disclose sexual orientation to their physicians, but little, if anything, is known about black lesbians. Black women, self-identified as bisexuals (N = 65) and lesbians (N = 529), were asked whether they had disclosed their homosexual behavior to their physicians. In the sample, only a third of the women had. Previous sexual experiences, both heterosexual and homosexual, were also queried to illuminate patterns of gynecologic health risk factors. Nearly all of the women reported previous heterosexual experiences.     

Sequence variation in the androgen receptor gene is not a common determinant of male sexual orientation.

To test the hypothesis that DNA sequence variation in the androgen receptor gene plays a causal role in the development of male sexual orientation, we have (1) measured the degree of concordance of androgen receptor alleles in 36 pairs of homosexual brothers, (2) compared the lengths of polyglutamine and polyglycine tracts in the amino-terminal domain of the androgen receptor in a sample of 197 homosexual males and 213 unselected subjects, and (3) screened the the entire androgen receptor coding region for sequence variation by PCR and denaturing gradient-gel electrophoresis (DGGE) and/or single-strand conformation polymorphism analysis in 20 homosexual males with homosexual or bisexual brothers and one homosexual male with no homosexual brothers, and screened the amino-terminal domain of the receptor for sequence variation in an additional 44 homosexual males, 37 of whom had one or more first- or second-degree male relatives who were either homosexual or bisexual. These analyses show that (1) homosexual brothers are as likely to be discordant as concordant for androgen receptor alleles; (2) there are no large-scale differences between the distributions of polyglycine or polyglutamine tract lengths in the homosexual and control groups; and (3) coding region sequence variation is not commonly found within the androgen receptor gene of homosexual men. The DGGE screen identified two rare amino acid substitutions, ser205-to-arg and glu793-to-asp, the biological significance of which is unknown.     

The Effects of Hypnotherapy on Homosexuality

Fifteen homosexuals were treated with hypnosis. The patients were selected from a general psychiatric practice and had a long history of confirmed homosexual behaviour and showed no evidence of organic or psychotic illness. The type of hypnotic induction attempted in all cases is described. In those where a satisfactory depth of hypnotic trance was achieved a change in sexual orientation was suggested to the patient.Before therapy, each patient was assessed using the Kinsey scale. Results were evaluated in terms of the patient''s subsequent behaviour and his subjective feelings. Of the 15 patients, three showed no improvement, four showed a mild improvement and eight showed a marked improvement. There was a significant correlation between the depth of hypnosis achieved and the therapeutic outcome. Those patients who reached a deep level of hypnotic trance were most likely to show a marked improvement. There were no significant correlations with other factors such as degree of homosexuality as measured on the Kinsey scale and the patient''s marital status.Treatment of homosexuals with hypnosis may produce more satisfactory results than those obtainable by other means. The best results are likely to be achieved in patients who are good hypnotic subjects.     

Biological and psychosocial determinants of male and female human sexual orientation

Some propositions on male and female sexual orientation will be considered. Some of these are established; others are more speculative. The aim is to offer some notes towards a coherent, comprehensive theory of sexual orientation. 1. The distinction between butch and femme lesbians seems real rather than a social construct. 2. High levels of prenatal steroid hormones seem to be causally associated with the sexual orientation of butch lesbians. However it is not established whether the causal process operates prenatally or postnatally (or both). This is so because prenatal hormone levels are thought to correlate positively with postnatal hormone levels. And high postnatal hormone levels may facilitate homosexual behaviour as a consequence of sensation-seeking. 3. Male bisexuals also are interpreted to have been exposed to high prenatal testosterone levels. But (for reasons similar to those outlined above in regard to butch lesbians) it is unclear whether these have a direct prenatal effect on the brain or whether they are precursors of high postnatal testosterone levels, which are associated with male bisexual orientation by promoting sensation-seeking behaviour. 4. Postnatal learning processes seem to be causally involved in the sexual orientation of some femme lesbians and some exclusive male homosexuals. 5. Some homosexual men have genes that predispose to their sexual orientation. 6. The same may apply to some lesbians, but such genes have not, as far as I know, been identified. 7. People (of both sexes) who engage in same-sex sexual behaviour may be classified simultaneously in two ways, viz (1) 'active' vs 'passive' and (2) those who do and those who do not engage (or consider engaging) in sex with members of the opposite sex. Ex hypothesi, some of the 'active' ones initiate some of the 'passive' ones. The active ones are driven more by hormones and the passive ones by psychosocial factors. The active males contain a substantial proportion of self-identified bisexuals; and the active females a substantial proportion of self-identified butches. 8. These two active categories (butch lesbians and male bisexuals) share a number of endocrinological, psychological, morphological and behavioural features vis-a-vis their exclusively homosexual and heterosexual peers. Methods of testing some of these ideas are presented.     

Homosexual women have less grey matter in perirhinal cortex than heterosexual women

Is sexual orientation associated with structural differences in the brain? To address this question, 80 homosexual and heterosexual men and women (16 homosexual men and 15 homosexual women) underwent structural MRI. We used voxel-based morphometry to test for differences in grey matter concentration associated with gender and sexual orientation. Compared with heterosexual women, homosexual women displayed less grey matter bilaterally in the temporo-basal cortex, ventral cerebellum, and left ventral premotor cortex. The relative decrease in grey matter was most prominent in the left perirhinal cortex. The left perirhinal area also showed less grey matter in heterosexual men than in heterosexual women. Thus, in homosexual women, the perirhinal cortex grey matter displayed a more male-like structural pattern. This is in accordance with previous research that revealed signs of sex-atypical prenatal androgenization in homosexual women, but not in homosexual men. The relevance of the perirhinal area for high order multimodal (olfactory and visual) object, social, and sexual processing is discussed.     

The ratio of 2nd to 4th digit length and male homosexuality

Sexual orientation may be influenced by prenatal levels of testosterone and oestrogen. There is evidence that the ratio of the length of 2nd and 4th digits (2D:4D) is negatively related to prenatal testosterone and positively to oestrogen. We report that (a) 2D:4D was lower in a sample of 88 homosexual men than in 88 sex- and age-matched controls recruited without regard to sexual orientation, (b) within the homosexual sample, there was a significant positive relationship between mean 2D:4D ratio and exclusive homosexuality, (c) overall, there was a decrease in 2D:4D from controls to homosexual men to bisexual men and (d) fraternal birth order, a positive predictor of male homosexuality, was not associated with 2D:4D in a sample of 240 Caucasian men recruited without regard to sexual orientation and 45 homosexual men.Further work is needed to confirm the relationships between 2D:4D and sexual orientation. However, these and other recent data tend to support an association between male homosexuality and high fetal testosterone. Very high testosterone levels may be associated with a sexual preference for both men and women.     

Seminal fluid excretion of cytomegalovirus related to immunosuppression in homosexual men.

Seminal fluid samples from 84 Danish homosexual men were successfully cultured to determine the prevalence of cytomegalovirus excretion. Ten (15%) out of 66 men positive for the antibody were found to be excreting the virus. Although the proportion excreting was inversely related to age (p less than 0.01), three men aged over 30 and with many years of homosexual experience excreted the virus. In addition, a 50 year old man with Kaposi''s sarcoma excreted the virus. A further study of the ratio of T cell helpers to suppressors in the men aged over 30 and a series of age matched non-excreting homosexual control or heterosexual men showed that those excreting cytomegalovirus in their seminal fluid had statistically lower ratios (all less than 0.77) than the controls (p less than 0.05). Excretion of cytomegalovirus may be related to re-emergence of latent infection in immunosuppressed homosexual men.     

Epigenetics and the maintenance of developmental plasticity: extending the signalling theory framework

Developmental plasticity, a phenomenon of importance in both evolutionary biology and human studies of the developmental origins of health and disease (DOHaD), enables organisms to respond to their environment based on previous experience without changes to the underlying nucleotide sequence. Although such phenotypic responses should theoretically improve an organism's fitness and performance in its future environment, this is not always the case. Herein, we first discuss epigenetics as an adaptive mechanism of developmental plasticity and use signaling theory to provide an evolutionary context for DOHaD phenomena within a generation. Next, we utilize signalling theory to identify determinants of adaptive developmental plasticity, detect sources of random variability – also known as process errors that affect maintenance of an epigenetic signal (DNA methylation) over time, and discuss implications of these errors for an organism's health and fitness. Finally, we apply life‐course epidemiology conceptual models to inform study design and analytical strategies that are capable of parsing out the potential effects of process errors in the relationships among an organism's early environment, DNA methylation, and phenotype in a future environment. Ultimately, we hope to foster cross‐talk and interdisciplinary collaboration between evolutionary biology and DOHaD epidemiology, which have historically remained separate despite a shared interest in developmental plasticity.     

Birth order and sexual orientation in men: evidence for two independent interactions

Birth order is correlated with male sexual orientation, but the reason(s) for this relationship is unclear. In the present study, data from a Canadian sample of homosexual and heterosexual men (N=604) were used to present evidence of two independent birth order interactions--one with height and the other with parental age--predicting sexual orientation in men. If these findings prove reliable, it raises the possibility that different aetiological factors underlie the birth order/sexual orientation relationship in men.     

野生川金丝猴一个全雄青年猴群的同性爬背行为

本研究采用行为取样方法,首次对秦岭野生川金丝猴全雄青年群中的同性爬跨行为进行报道。研究中我们共观察到21 次同性爬背行为,其平均持续时间为5.53 ± 3.11s;雄性同性爬背发生前的行为中以玩耍行为(47.62% )和3 种不同姿势的邀配模仿行为(42.85% )为主;而同性爬背行为发生后则主要为彼此间的相互理毛行为(47.62% )和玩耍行为(23.81% )。对比先前婴幼猴时期的相关研究结果,青年猴同性爬背行为前邀配模仿资势的多样化在一定程度上体现了野生状态下雄性川金丝猴个体青少年阶段的性行为发育进程。考虑到川金丝猴全雄群的社会结构,青年猴同性爬背行为具有巩固社群稳定和加强个体关系的功能。此外,研究中观察到76.19% 的同性爬背行为发生在昼间休息期之后的第一个小时内,这可能是“睡眠与觉醒循环”对性激素的反调节作用所致。     

Hennig's semaphoront concept and the use of ontogenetic stages in phylogenetic reconstruction

A new practice in systematics, “semaphoront” coding, treats developmental stages as terminals, and it derives from Hennig's concept of the same name. Semaphoront coding has been implemented recently by Lamsdell and Selden (BMC Evol. Biol., 2013, 13:98) and Wolfe and Hegna (Cladistics, 2014, 30:366) in an effort to understand the relationships of fossil taxa of unknown developmental stage. We submit that this approach is antithetical to cladistic practice and constitutes a gross misunderstanding of Hennig's original idea. Here we review the concept of the semaphoront and clarify the role of the semaphoront in phylogenetic systematics. We contend that treating ontogenetic stages as terminals both violates tenets of phylogenetic systematics and oversimplifies the complexity of developmental processes. We advocate Hennig's alternative of including data from as many semaphoronts as possible, but implemented using the superior total evidence framework. Finally, we contend that the application of semaphoront coding to any palaeontological question requires invoking multiple, unjustified assumptions, and ultimately will not yield a possible phylogenetic solution. A total evidence approach can grapple with the placement of fossil developmental stages, if only imperfectly.     

Possible Balancing Selection in Human Female Homosexuality

A growing number of researchers suggest that female homosexuality is at least in part influenced by genetic factors. Unlike for male homosexuality, few familial studies have attempted to explore maintenance of this apparently fitness-detrimental trait in the population. Using multiple recruitment methods, we explored fecundity and sexual orientation within the pedigrees of 1,458 adult female respondents. We compared 487 homosexual and 163 bisexual with 808 heterosexual females and 30,203 of their relatives. Our data suggest that the direct fitness of homosexual females is four times lower than the direct fitness of heterosexual females of corresponding ages. The prevalence of nonheterosexuality within the homosexual female respondents’ families (2.83%) appear to be more than four times higher than the basal prevalence in the Italian population (0.63%). Pedigree size and relative fecundity in both the paternal and maternal sides of the homosexual women’s families were significantly higher than in the heterosexuals’ families. If confirmed, the relative average fecundity increase within the family seems to offset the loss in fitness due to the low direct fitness of homosexual females. Therefore, the balanced fecundity in the homosexual females’ families may allow the trait to be maintained at a low-frequency equilibrium in the population.